I am asking this question as I have not seen an answer to the question (that I can understand) as of yet (Credit for original question: Series expansion of infinite series raised to the $n$th power)
Can anyone explain how you can do it for an infinite $$\left( \sum_{n\in \mathbb N} \ f(x,n) \right)^n$$
Sorry for the bad explanation, linking and other stuff, I am not familiar with this site, but please explain the answer to this question as I am not quite familiar with infinite sums yet